In the manufacture of various types of tissue products such as facial tissue, bath tissue, paper towels and the like, the dried tissue web or tissue sheet coming off of the tissue machine is initially wound into a parent roll and temporarily stored for further processing. Sometime thereafter, the parent roll is unwound and the tissue web is converted into a final product form.
In winding the tissue web into a large parent roll, it is vital that the roll be wound in a manner which prevents major defects in the roll and which permits efficient conversion of the roll into the final product, whether it be boxes of facial tissue sheets, rolls of bath tissue, rolls of embossed paper towels, and the like. Ideally, the parent roll has an essentially cylindrical form, with a smooth cylindrical major surface and two smooth, flat, and parallel end surfaces. The cylindrical major surface and the end surfaces should be free of ripples, bumps, waviness, eccentricity, and wrinkles, i.e. the roll should be substantially uniform. Likewise, the parent roll must be stable, so that it does not depart from its cylindrical shape during storage or routine handling, i.e. the roll should be dimensionally stable. Defects can force entire parent rolls to be scrapped if they are rendered unsuitable for high speed conversion.
A variety of reels have been developed for the winding of paper webs into parent rolls including a reel having an endless flexible belt, such as the reel disclosed in U.S. Pat. No. 5,901,918. In particular, tissue webs having a bulk of about 10 cubic centimeters per gram (cc/g) or higher and a high level of softness, as characterized, for example, by a machine direction slope of about 10 kilograms or less per 3 inches (kg/3″) of sample width are especially suited to winding on such reels. Such reels and winding methods can be used to produce substantially uniform and dimensionally stable parent rolls of such soft tissue webs having diameters on the order of 70 to 150 inches.
While belted reels, such as those disclosed in U.S. Pat. No. 5,901,918, are effective at winding soft, high bulk tissue webs, as the machine speed of the belted reel is increased, web handling can become a problem. In particular, the tissue web can wander or be loosely affixed to the transfer belt, causing an uneven parent roll during winding and/or problems in effecting an efficient transfer to a new reel spool during a transfer when the tissue web is changed from winding onto the full diameter parent roll and directed to winding on a new reel spool. One method of solving this problem is to use vacuum boxes beneath the transfer belt to securely hold the tissue web to the transfer belt, as disclosed in U.S. Pat. No. 6,698,681. However, such a solution requires an air permeable transfer belt, which may not always be desirable. Additionally, vacuum boxes are prone to becoming plugged with excess tissue dust and can be a fire or explosion hazard. The exhaust must be sent to a dust removal system, which adds more cost and complexity. Vacuum boxes and dust removal systems require frequent cleanings to ensure safe, reliable operation. Vacuum boxes are only effective to control the tissue web in the immediate area where they are located, and it is difficult to locate them along the entire length of the transfer belt in the reel section. Finally, transfer belt wear can be an issue if tissue dust builds up between the vacuum box and the fabric.
Therefore, there is still a need for an apparatus and method of winding paper webs, especially bulky tissue webs, at faster production speeds having improved web stability in order to wind more uniform parent rolls. There is also still a need for an apparatus and method for maintaining especially good tissue web control during a transfer to manufacture such webs cost effectively.